diff --git a/swh/loader/svn/replay.py b/swh/loader/svn/replay.py
--- a/swh/loader/svn/replay.py
+++ b/swh/loader/svn/replay.py
@@ -508,22 +508,35 @@
             )
             self.externals = defaultdict(list)
             if value is not None:
-                # externals are set on that directory path, parse and store them
-                # for later processing in the close method
-                for external in value.split("\n"):
-                    external = external.rstrip("\r")
-                    # skip empty line or comment
-                    if not external or external.startswith("#"):
-                        continue
-                    (
-                        path,
-                        external_url,
-                        revision,
-                        relative_url,
-                    ) = parse_external_definition(
-                        external, os.fsdecode(self.path), self.svnrepo.origin_url
+                try:
+                    # externals are set on that directory path, parse and store them
+                    # for later processing in the close method
+                    for external in value.split("\n"):
+                        external = external.rstrip("\r")
+                        # skip empty line or comment
+                        if not external or external.startswith("#"):
+                            continue
+                        (
+                            path,
+                            external_url,
+                            revision,
+                            relative_url,
+                        ) = parse_external_definition(
+                            external, os.fsdecode(self.path), self.svnrepo.origin_url
+                        )
+                        self.externals[path].append(
+                            (external_url, revision, relative_url)
+                        )
+                except ValueError:
+                    logger.debug(
+                        "Failed to parse external: %s\n"
+                        "Externals defined on path %s will not be processed",
+                        external,
+                        self.path,
                     )
-                    self.externals[path].append((external_url, revision, relative_url))
+                    # as the official subversion client, do not process externals in case
+                    # of parsing error
+                    self.externals = {}
 
             if not self.externals:
                 # externals might have been unset on that directory path,
diff --git a/swh/loader/svn/tests/test_externals.py b/swh/loader/svn/tests/test_externals.py
--- a/swh/loader/svn/tests/test_externals.py
+++ b/swh/loader/svn/tests/test_externals.py
@@ -1482,3 +1482,94 @@
         type="svn",
     )
     check_snapshot(loader.snapshot, loader.storage)
+
+
+def test_loader_with_externals_parsing_error(
+    swh_storage, repo_url, external_repo_url, tmp_path
+):
+    # first commit on external
+    add_commit(
+        external_repo_url,
+        "Create code directory",
+        [
+            CommitChange(
+                change_type=CommitChangeType.AddOrUpdate,
+                path="code/",
+            ),
+        ],
+    )
+
+    # second commit on external
+    add_commit(
+        external_repo_url,
+        "Create code/foo.sh file",
+        [
+            CommitChange(
+                change_type=CommitChangeType.AddOrUpdate,
+                path="code/foo.sh",
+                properties={"svn:executable": "*"},
+                data=b"#!/bin/bash\necho foo",
+            ),
+        ],
+    )
+
+    # first commit
+    add_commit(
+        repo_url,
+        "Create trunk directory.",
+        [
+            CommitChange(
+                change_type=CommitChangeType.AddOrUpdate,
+                path="trunk/",
+            ),
+        ],
+    )
+
+    # second commit
+    add_commit(
+        repo_url,
+        "Set external on trunk directory that will result in a parsing error.",
+        [
+            CommitChange(
+                change_type=CommitChangeType.AddOrUpdate,
+                path="trunk/",
+                properties={
+                    "svn:externals": (
+                        f"-r2{svn_urljoin(external_repo_url, 'code/foo.sh')} foo.sh"
+                    )
+                },
+            ),
+        ],
+    )
+
+    # third commit
+    add_commit(
+        repo_url,
+        "Fix external definition on trunk directory.",
+        [
+            CommitChange(
+                change_type=CommitChangeType.AddOrUpdate,
+                path="trunk/",
+                properties={
+                    "svn:externals": (
+                        f"-r2 {svn_urljoin(external_repo_url, 'code/foo.sh')} foo.sh"
+                    )
+                },
+            ),
+        ],
+    )
+
+    loader = SvnLoader(
+        swh_storage,
+        repo_url,
+        temp_directory=tmp_path,
+        check_revision=1,
+    )
+    assert loader.load() == {"status": "eventful"}
+    assert_last_visit_matches(
+        loader.storage,
+        repo_url,
+        status="full",
+        type="svn",
+    )
+    check_snapshot(loader.snapshot, loader.storage)